An axial flow, gas turbine engine has a compression section, a combustion section and a turbine section. An axial flow path for working medium gases extends through these sections of the engine. The working medium gases are compressed in the compression section. The compressed gases are mixed with fuel in the combustion section and burned to add energy to the gases. The hot, pressurized gases are expanded through the turbine section where work is extracted from the gases.
Examples of typical fuel supply systems which provide for fuel and water mixing and dividing arrangements are shown in U.S. Pat. No. 4,214,435 entitled "Method For Reducing Nitrous Oxide Emissions Form A Gas Turbine Engine" issued to Campbell and U.S. Pat. No. 4,918,925 entitled "Laminar Flow Fuel Distribution System" issued to Tingle.
One device for delivering fuel to the combustion section is a fuel nozzle or fuel injector. The fuel injector may have a relative pressure drop in comparison to the pressure drop of the fuel supply system which is relatively high. In such constructions, maldistribution of the fuel supplied to the plurality of fuel injectors is not a concern. Maldistribution is small, because the fuel supply system pressure drop is small in comparison to the pressure drop of the fuel injector and that pressure drop, which is the same for all fuel injectors, remains relatively constant between injectors for a given flow rate.
Another type of fuel nozzle or fuel injector has a very relatively low pressure drop in comparison to the pressure drop of the fuel supply system. An example of such a fuel injector is shown in U.S. Pat. No. 4,977,740 entitled "Dual Fuel Injector" issued to Thomas J. Madden, Barry C. Schlein, and W. Barry Wagner, which is assigned to the Assignee of this Application. This particular fuel injector uses both gaseous and liquid fuels and is designed to operate with water injection system for supplying water to the burning fuel to reduce the formation of nitrous oxides (NOx).
Maldistribution problems are a particular concern in such arrangements because the fuel injector pressure drop is relatively small and the fuel supply system must operate over a wide flow range. For example, water flow rates which are up to one and a half (11/2) times the fuel flow rate may be required to control emissions.
Large manifold pipes are necessary to accommodate the highest combined flow rates with reasonable pressure losses as dictated by the maximum fuel pump output capacity. At low flow rates, such as the engine starting condition, the length of time to fill the manifold pipes prior to commencing the starting sequences are excessively long.
Accordingly, scientist and engineers working under the direction of Applicants' Assignee have sought to develop a fuel supply system which can accommodate a wide range of flow rates and a wide range of water-fuel ratios during operative conditions while minimizing maldistribution problems.